Studies of estrogenic hormones effects on uterine biochemistry will be continued. Emphasis will be placed on developing uterine cell cultures in which the turnover, synthesis and replenishment of estrogen receptors can be studied. This will also necessitate looking for physiological responses of the cells to estrogens added to the cultures. Protein and DNA synthesis responses will be studied by incorporation of precursors. Estrogen receptors in various states and subcellular fractions will be assessed by binding of labeled estrogens.